Telescopic crane jib

ABSTRACT

A telescopic crane jib comprises a number of telescopic parts which can be extended and locked end to end without substantial overlap. The parts are extended and retracted when the jib is vertical by means of a fluid pressure operated cylinder whose piston rod extends downwards from the cylinder and is fixed to the lower end of a housing which surrounds the telescopic parts in their contracted state. The housing is in fact in two telescopic parts for ease of transport, but whenever the jib is to be used the housing is extended to its active length of substantially twice that of each of the telescopic jib parts. The telescoping cylinder acts on the telescopic jib parts through a supporting carrier which is fixed on the lower end of the cylinder below the telescopic parts and which is arranged to engage guide surfaces within the lower portion of the housing. In extending the jib the cylinder is raised to lift the contracted telescopic parts so that a catch mechanism at the top of a housing engages and holds the upper end of the upper telescopic part. The cylinder is then lowered taking with it the other telescopic parts. In the lower position the lower end of the upper telescopic part can be locked to the upper end of the next telescopic part by means of a locking mechanism comprising a bolt housed in the lower end of the upper part and arranged to engage in a bore in the next part. The catch mechanism is released and the cylinder is again raised, pushing the extended upper part of the housing until the upper end of the next part engages the catch mechanism. The process is repeated until the lowest telescopic part is raised into the upper portion of the housing. The cylinder and its supporting carrier are then lowered on their own, and means is provided for connecting the upper end of the cylinder with the lower end of the lower telescopic part so that the cylinder can be again raised to extend the telescopic parts further from the housing.

United States Patent 1191 Eucken 14 1 Nov. 5, 1974 TELESCOPIC CRANE JIB [73] Assignee: Leo Gottwald KG,

Dusseldorf-Holthausen, Germany [22] Filed: Sept. 25, 1973 [21] Appl. No.: 400,652

[30] Foreign Application Priority Data Sept. 28, 1972 Germany 2247491 Oct. 7, 1972 Germany 2249309 52 11.s.c1 212/64, 212/33,.212/57 [51] Int. Cl. B66c 23/02 [58] Field of Search 212/64, 33; 187/57, 9

[56] References Cited UNITED STATES PATENTS 1,907,024 5/1933 Willard et al. 212/33 x 3,715,014 2/1973 Ohta 187/9 3,774,727 11/1973 Berkestad 187/9 FOREIGN PATENTS OR APPLICATIONS 1,023,182 3/1953 France 212/64 1,264,080 5/1961 France 212/64 Primary Examiner-Robert J. Spar Assistant ExaminerR. Johnson Attorney, Agent, or Firm-Toren, McGeady and Stanger [57] ABSTRACT A telescopic crane jib comprises a number of telescopic parts which can be extended and locked end to end without substantial overlap. The parts are extended and retracted when the jib is vertical by means of a fluid pressure operated cylinder whose piston rod extends downwards from the cylinder and is fixed to the lower end of a housing which surrounds the telescopic parts in their contracted state. The housing is in fact in two telescopic parts for ease of transport, but

whenever the jib is to be used the housing is extended to its active length of substantially twice that of each of the telescopic jib parts. The telescoping cylinder acts on the telescopic jib parts through a supporting carrier which is fixed on the lower end of the cylinder below the telescopic parts and which is arranged to engage guide surfaces within the lower portion of the housing. In extending the jib the cylinder is raised to lift the contracted telescopic parts so that a catch mechanism at the top of a housing engages and holds the upper end of the upper telescopic part. The cylinder is then lowered taking with it the other telescopic parts. In the lower position the lower end of the upper telescopic part can be locked to the upper end of the next telescopic part by means of a locking mechanism comprising a bolt housed in the lower end of the upper part and arranged to engage in a bore in the next part. The catch mechanism is released and the cylinder is again raised, pushing the extended upper part of the housing until the upper end of the next part engages the catch mechanism. The process is repeated until the lowest telescopic part is raised into the upper portion of the housing. The cylinder and its supporting carrier are then lowered on their own, and means is provided for connecting the upper end of the cylinder with the lower end of the lower telescopic part so that the cylinder can be again raised to extend the telescopic parts further from the housing.

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1. In a telescopic crane jib including a plurality of individual telescopic parts, means for extending and retracting said parts when the longitudinal axis of said jib is at least substantially vertical, locking means for locking said parts positively together when said parts are extended, and a jib housing surrounding said telescopic parts when said parts are retracted, the improvement wherein said means for extending and retracting said telescopic parts is a fluid pressure operated cylinder mounted for vertical movement within said housing and there is means associated with the lower end of said cylinder below the lowest of said telescopic parts for guiding said cylinder vertically in a lower portion of said housing, and said locking means are situated at the ends of said telescopic parts and include means for locking said parts together end to end.
 2. A crane jib as claimed in claim 1, wherein said means associated with said lower end of said extending and retracting cylinder comprises a supporting carrier for supporting said telescopic parts when said parts are retracted, and means mounting said supporting carrier to said cylinder, said supporting carrier engaging said lower portion of said housing in vertically guiding said cylinder.
 3. A crane jib as claimed in claim 2, wherein said supporting carrier is provided with rollers, and said lower portion of said housing has guide surfaces on which said rollers run in guiding said cylinder.
 4. A crane jib as claimed in claim 1, further comprising means for releasably connecting the upper end of said extending and retracting cylinder to the lower end of the lowest of said telescopic parts.
 5. A crane jib as claimed in claim 4, wherein said releasable connecting means comprises a connecting bolt, means mounting said bolt on said lowest telescopic part for displacement transverse to the longitudinal axis of said jib, and means on said cylinder for engagement with said bolt when said bolt is displaced.
 6. A crane jib as claimed in claim 5, wherein said means mounting said bolt comprises a tube receiving said bolt and having its axis transverse to the longitudinal axis of said jib, and a pneumatically operated piston is provided for applying pressure to displace said bolt in said tube.
 7. A crane jib as claimed in claim 2, further comprising at least one lifting drum for a hoist mechanism of said crane jib, said at least one lifting drum being mounted on said supporting carrier.
 8. A crane jib as claimed in claim 7, further comprising a drive mechanism for said at least one lifting drum, said drive mechanism also being mounted on said supporting carrier.
 9. A crane jib as claimed in claim 1, wherein said jib housing comprises an upper portion separate from said lower portion and mounted for telescopic extension and retraction relative to said lower portion, means on said upper portion for connecting said upper portion through said telescopic jib parts to said extending and retracting cylinder whereby said cylinder is used to extend and retract said upper portion of said housing.
 10. A crane jib as claimed in claim 1, wherein said means for locking Each adjacent pair of said telescopic parts end to end comprises a guide tube mounted at the lower end of the upper of said pair of telescopic parts, a locking bolt mounted for displacement in said guide tube, a double acting fluid pressure operated cylinder for displacing said locking bolt in said guide tube, means defining a locking bore in the upper end of the lower of said pair of telescopic parts for receiving said locking bolt when said bolt is displaced from said guide tube, and cooperating means on said telescopic parts for determining alignment of said locking bolt with said locking bore.
 11. A crane jib as claimed in claim 1, further comprising a catch mechanism disposed at the upper end of said tube housing, said catch mechanism including a guide tube mounted on said housing, a catching bolt mounted in said guide tube for displacement therein, and a double acting fluid pressure operated cylinder for displacing said catching bolt in said guide tube, means defining a catching bore at the upper end of each of said telescopic parts for receiving said catching bolt, and cooperating means on said catch mechanism and said telescopic parts which engage each other when said catching bolt is aligned with one of said catching bores.
 12. A crane jib as claimed in claim 11, wherein said guide tube, and hence said catch mechanism, is mounted for displacement through a limited distance in the vertical direction, and there is provided means for controlling operation of said cylinder for displacing said catching bolt in dependence upon the vertical position of said catch mechanism relative to said housing.
 13. A crane jib as claimed in claim 10, wherein said locking means includes a sleeve surrounding said locking bolt and axially slidably mounted in said guide tube, said sleeve forming part of said cooperating means for determining alignment of said bolt with said locking bore.
 14. A crane jib as claimed in claim 13, wherein said locking bolt has a reduced diameter shank portion at its end adjacent its operating cylinder, and an end plate is mounted in said sleeve surrounding said locking bolt and is provided with means defining a bore through which said shank portion extends, said end plate serving as a stop surface for said locking bolt.
 15. A crane jib as claimed in claim 14, including a compression spring disposed for action between said end plate and said operating cylinder whereby said sleeve is urged by said spring away from said cylinder.
 16. A crane jib as claimed in claim 14, wherein said sleeve has a nose at its end remote from said end plate, and said lower of said pair of telescopic parts is provided with a member which engages with said nose when said pair of parts are locked end to end to prevent removal of said locking bolt from said locking bore.
 17. A crane jib as claimed in claim 16, wherein said lower of said pair of telescopic parts has a stop plate displaced from said member for engaging with said nose, said stop plate being displaced from said member by substantially the length of said nose and said stop plate including said means defining said locking bore.
 18. A crane jib as claimed in claim 17, including a reinforcing plate mounted on said stop plate and having means defining a bore in registry with said locking bore.
 19. A crane jib as claimed in claim 10, wherein the lower of said pair of telescopic parts is provided with a stop at its upper end for engagement by said guide tube on the other of said pair of telescopic parts to prevent said parts from becoming disconnected.
 20. A crane jib as claimed in claim 19, wherein said stop and said guide tube form said cooperating means for determining alignment of said locking bolt and said locking bore.
 21. A crane jib as claimed in claim 19, wherein said stop is provided with a slot, a double armed rocker is pivotally mounted above said guide tube, and a sensor for controlling operation of said cylinder for moving said locking bolt is mounted for operation by said rocker, wherEby when said pair of telescopic parts are moved into position for being locked together one arm of said rocker is received in said slot in said stop and is caused to pivot to bring the other arm of said rocker into engagement with said sensor to cause movement of said locking bolt.
 22. A crane jib as claimed in claim 10, wherein said locking bolt is provided with a retaining groove at its free end.
 23. A crane jib as claimed in claim 10, wherein said cooperating means for determining alignment of said locking bolt with said locking bore comprises mating concave and convex surfaces respectively on the lower and upper of said pair of telescopic parts.
 24. A crane jib as claimed in claim 12, including a sleeve surrounding said catching bolt and axially slidably mounted in said guide tube, said sleeve forming part of said cooperating means for determining alignment of said catching bolt with a catching bore.
 25. A crane jib as claimed in claim 24, including compression spring disposed vertically for action between said housing and said catch mechanism, said vertical compression spring supporting said catch mechanism without external loading in a rest position which is substantially mid way between the upper and lower limits of displacement of said mechanism.
 26. A crane jib as claimed in claim 25, including a compression spring disposed horizontally for action on said sleeve surrounding said catching bolt to urge said sleeve into a position for engagement by the upper end of a telescopic part, said sleeve being urged into this position when said catch mechanism is in its rest position.
 27. A crane jib as claimed in claim 26, including a tube fixidly mounted to said housing, a stop carried by said tube, a further sleeve slidably mounted around said tube and welded to said guide tube whereby the axis of said further sleeve is perpendicular to the axis of said guide tube, and a cover fixed to said further sleeve at its end adjacent said guide tube, said vertically mounted spring acting between said stop and said cover.
 28. A crane jib as claimed in claim 27, including an entrainment bolt mounted for movement with said further sleeve, and means provided on said entrainment bolt for actuating said means for controlling the operation of said cylinder for moving said catching bolt.
 29. A crane jib as claimed in claim 28, wherein said catching bolt and said sleeve surrounding said bolt are retracted from a position of engagement with a telescopic part when said catching mechanism is at its upper limit of displacement.
 30. A crane jib as claimed in claim 29, wherein said catching bolt and said sleeve surrounding said catching bolt are in a projecting position for engaging a telescopic part when said catching mechanism is at its lower limit of displacement.
 31. A crane jib as claimed in claim 10, further comprising a push rod on said telescopic part carrying said locking bolt, a sensor for intiating retraction of said locking bolt and disposed for actuation by said push rod, a spring urging said push rod away from said sensor, and a mechanism mounted on said jib housing for displacing said push rod against the action of said spring to actuate said sensor when said telescopic part is correctly positioned relative to said housing and said telescopic parts are to be retracted. 